The secret of attractiveness is making other people smile, according to a study by British psychologists. Experiments at Aberdeen University found we are more likely to think a person is good-looking if we catch members of the opposite sex smiling at them.

Tests show that our taste is always swayed by the attention people receive from others. In the tests, women ranked men as substantially more appealing if they had been shown images of other women smiling at them. The psychologists believe men respond in the same way, suggesting both sexes subconsciously take account of their sexual competitors' views when judging the appeal of a potential partner.

"So when you're out in a bar, there's an advantage to being nice to everyone, because if they're smiling at you, it's going to make you more attractive," said Ben Jones, author of the paper in the Royal Society's biological research journal today.